648 PROCEEDINGS OP THE SOCIETY. 



papers before them, it would be necessary to postpone the discussion — 

 a postponement which was the less to be regretted, inasmuch as Dr. 

 Fripp had been kind enough to jironiise them a second paper on the 

 subject at an early date, when the discussion could take place with 

 the advantage of their having then had an opportunity of reading the 

 present paper in print. 



Er. W. M. Ord then stated the chief points in his paper, " On 

 some Causes of Brownian Movements." 



Mr. Wenham said that Dr. Ord appeared to have experimented on 

 substances which were liable to change, and inquired whether he 

 attributed the movements to decomposition, and whether they were 

 found eventually to cease. 



Dr. Ord said that the movements he had described went on as 

 long as they could be observed. Decomposition no doubt liad much to 

 do with the movement in question, but not jjutrofaction ; and chemical 

 metamorphoses appeared to jjlay a very important part in it. 



Mr. Wenham remembered about twenty years ago experimenting 

 with a mixture of oil and albumen, and in one case he obtained a very 

 curious effect : having confined some of the substance in a small 

 space so as to get a narrow channel full of molecules, he found that 

 when they could not move laterally, they kept up a continuous move- 

 ment along the channel in a manner which very closely resembled 

 cyclosis in plants. 



Dr. Ord mentioned another interesting experiment. If a small 

 quantity of white of egg was diluted with one-third its volume of 

 water, and to this was added one-tenth the quantity of liquor 

 potassse, and then some oil were mixed with it (by preference 

 neat's-foot oil), and this mixture were left for a fortnight or three 

 weeks, they would find in the first place a number of molecules 

 covered with laminae of coagulated albumen. In a certain number 

 of these they would find an interior globule with a pellicle of its own, 

 and sometimes they would also find these filled with a number of the 

 most minute molecules all engaged in the quickest possible Brownian 

 movements. 



Mr. Wenham said he had in his possession a slide of quartz con- 

 taining a small bubble of liquid — supposed to be carbonic acid — which 

 had a continuous motion, and this had been going on many years. 



Professor Kellicott's letter to Mr. Crisp as to Anuriea lonijispina, 

 described at p. 157, was read, in which he said, " It is a jjoor traveller, 

 and is at present known only in the water supplies of cities along 

 the Great Lakes, and obtained by filtering the water through muslin, 

 by which process a sediment of dirt and living forms is obtained, 

 with which the rotifer soon gets entangled, and then dies. When 

 they are plentiful, usually during the autumn, clean gatherings are 

 to be had. I have made many trials at capturing them since receiving 

 your letter asking me to send some, but thus far without success. I 

 will keep a look-out for them, and will send a good sample as soon as 

 they can be had." 



